2. edit public-yum-el5.repo
search for el5_addons entry. there are two addons, one is el_5addons, and another one is el5_oracle_addons. change the value of enabled from 0 to 1 to enable the both entries.

3. install ovmcli
# yum install ovmcli

cool thing about yum is that it handles the dependencies automatically, so you would easily avoid the possible hassles.